A new report says Seattle police may have been underreporting hate crimes.

This after Police Department’s own findings showed a substantial increase in hate crime reporting last year.

City of Seattle auditors determined that each of the past four years, officers wrote an average of 17,000 reports that listed the bias category as “unknown.”

Further, auditors note that four bias categories were never added to the department’s records system.

The report found that this could have resulted in underreporting.

SPD removed the option of using “unknown” from its bias category choices in July.

The report also says officers could benefit from more frequent formal training and guidance on hate crimes.

City Councilmember Lisa Herbold asked for the report. In a statement, she thanked the police department for responding to the report’s recommendations.

It’s the first of two reports the auditor’s office will release. The second will offer suggestions for how the city can improve its use of hate crime data.

In a statement Seattle police chief Kathleen O’Toole said the department routinely scrutinized its procedures. She said the department would work with the community “to remain a national model in preventing, responding to, and analyzing bias-based incidents.”